Strengths: Great line to shop if you're looking for well-formulated vitamin C and retinol products; some outstanding sunscreens (including for sensitive skin), and every one provides sufficient UVA protection; one effective AHA product; good self-tanner; several fragrance-free products.

Weaknesses: Mostly problematic cleansers and toners; fruit and sugar extracts trying to substitute for AHA products when the real deal is much better; ineffective BHA products; jar packaging; several overpriced products touting one superstar ingredient when skin does best with a cocktail of beneficial ingredients.

With a strong presence in the professional (meaning spa and aesthetics) skin-care market, SkinCeuticals has a mostly well-deserved reputation for producing serious-minded, research-driven products, several of which are centered on L-ascorbic acid. Company founder Dr. Sheldon Pinnell began the line after a falling out with the folks behind Cellex-C, a company for which Dr. Pinnell once served as spokesperson. The falling out had to do with both Cellex-C and Dr. Pinnell holding patents on L-ascorbic acid; Cellex-C held the patent on a formula with L-ascorbic acid (the original Cellex-C serum) while Dr. Pinnell's patent (now conspicuously absent from SkinCeuticals products) was only for the ingredient. The drama continued as, years later, the doctor who joined Pinnell to work on SkinCeuticals' vitamin C products began his own company, also selling products with vitamin C. Who needs Desperate Housewives when we have desperate doctors racing to be the authoritative word on the anti-aging properties of vitamin C?

The good news is that copious research has demonstrated that L-ascorbic acid (despite its stability issues, which, formula-wise, SkinCeuticals products do address) is a good, potent antioxidant and anti-inflammatory agent. It has also been shown to provide photoprotective benefits when skin is exposed to UV light and is capable of stimulating collagen production - though don't take that to mean it is a cure for wrinkles (Sources: International Journal of Toxicology, 2005, supplement, pages 51–111; Experimental Dermatology, June 2003, pages 237–244; Dermatologic Surgery, March 2002, pages 231–236; Bioelectrochemistry and Bioenergetics, May 1999, pages 453–461; and International Journal of Radiation Biology, June 1999, pages 747–755). Of course, other forms of vitamin C have equally impressive research, and some forms, such as magnesium ascorbyl phosphate, have better stability profiles (Source: Journal of Pharmaceutical and Biomedical Analysis, March 1997, pages 795–801).

As we've mentioned before, vitamin C is but one of many good antioxidants, and it's not the best approach to select any one or two antioxidants and bank on them alone to provide every conceivable skin-rejuvenating benefit. Instead, go for products that offer a cocktail of antioxidants because you'll get a greater range of benefits. Plus, some antioxidants in combination have a synergistic effect that surpasses what occurs when any of the ingredients are used alone. SkinCeuticals clearly knows this, because their vitamin C products also contain the antioxidant ferulic acid, and some add vitamin E to the mix as well. Above all, remember that as multifunctional as antioxidants are, they cannot stop aging, they won't eliminate wrinkles, and they do not replace the need for daily sun protection.

L'Oreal purchased SkinCeuticals in May 2005, and, for the time being, seems to be letting them stay on their course. That's a good thing, because despite L'Oreal’s considerable financial reserves and global R&D team, the skin-care products their brands produce consistently lag behind what current research indicates are state-of-the-art options. As long as they continue to let SkinCeuticals retain its stature, there are many good reasons to shop this line; however, that said, this line is far from perfect in terms of being able to assemble a complete skin-care routine. Focusing on what they do best (which is serums, sunscreens, and specialty products) will be money well spent for visible results. Those who find the SkinCeuticals price tags to be a deal-breaker need to know that despite several notable products, they're hardly the only game in town; you can find equally superior products for less money, though not all of them follow the impressive concentration protocols of SkinCeuticals.